Spike Jonze’s last film, the suffocatingly self-indulgent Where the Wild Things Are, gave us some cause for concern. Maybe Jonze without Charlie Kaufman – hitherto his regular writer – would forever be as unappealing as Wise without Morecambe. Well, he’s certainly shown us.

Her , Jonze’s extraordinary speculative romance, certainly has the look of a dispatch from Hipster Central. The director has employed Hoyte van Hoytema, the hot Dutch cinematographer who created cold images for Let the Right One In , to spread his smoky, over-rinsed glaze across an alienating urban landscape. Joaquin Phoenix and fellow actors cope admirably with costumes (absurdly high-waist pants, mustard boots) that appear to pastiche the daywear of Williamsburg cheese salesman. The strong score is by Arcade Fire, for Pete’s sake.

However, for all its clever-clever shapes, Her exhibits real emotional traction from odd beginning to melancholy ending.

The pitch is easy to summarise. Making good use of his diagonal smile and worried brow, Phoenix plays Theodore Twombly, a lonely man who falls in love with the voice on his computer’s operating system.

Her can, thus, be viewed as a benign variation on 2001: A Space Odyssey . But the new story is, if anything, made more disturbing by our greater nearness to the technology. Few images in recent cinema have been quite so poignant as the vision of Theodore, enthusiast for a videogame that takes up virtual space in his living room, feebly trying to persuade the robotic protagonist to ascend a tumbling sand dune. We’ve all been there.

Reasonably soon we may encounter an OS like the one who identifies herself to Theodore as “Samantha”. Voiced by Scarlett Johansson, the programme assumes an informal manner with its user as it sets about reorganising his emails and tidying up his contacts. Gradually the conversations get more intimate and, before too long, Theodore has resigned himself to the fact that he is in a relationship with a disembodied artificial consciousness.

It seems that everybody is doing it. Theodore’s mate Amy (Amy Adams) soon announces that her own interface has become a bosom chum.

Jonze’s wisest move was to position the film’s universe at a gentle angle to our own. This is not the full-on, existential wonderland of Being John Malkovich . It’s as familiar as it is strange. Theodore works for a company that composes intimate letters for those unable to express themselves effectively. That seems possible. The computer hardware dabbles in the sort of mild retro-chic – smart-phones look a little like 1950s cigarette cases – that we fully expect from Apple’s successors. The film is set in LA, but, to heighten the alienation, many of the urban exteriors were shot in Singapore.

Most significantly, the characters seem fully prepared for the change in romantic dynamics signified by the protagonist’s lunge into cyber-love. When Theodore tells his estranged wife (Rooney Mara) that he is dating his OS, she doesn’t suggest that he contact a psychiatrist, but merely notes that this indicates his unwillingness to tackle the complexities of a “real” relationship.

Therein lurks the film’s big theme. All the best science fiction on artificial intelligence is really about the challenges of being human. Her is full of strong, sly jokes and intriguing speculation on future technologies. But, ultimately, it is a sad story about the difficulty of making meaningful connection with any psyche, whether organically evolved or digitally tailored to the user’s needs.

Joaquin Phoenix has just the face for such a story. As Her slips into an inevitable melancholy, it becomes less about trans-humanity and more about, well, humanity. Maybe it was a little cruel of the distributors to release their sad near-masterpiece on Valentine’s Day.